PSR J1119-6127 and the X-ray Emission from High Magnetic Field Radio Pulsars

The existence of radio pulsars having inferred magnetic elds in the magnetar regime suggests that possible transition objects could be found in the radio pulsar population. The discovery of such an object would contribute greatly to our understanding of neutron star physics. Here we report on unusual X-ray emission detected from the radio pulsar PSR J1119-6127 using XMM-Newton. The pulsar has a characteristic age of 1,700 yrs and inferred surface dipole magnetic eld strength of 4.1x10^13 G. In the 0.5-2.0 keV range, the emission shows a single, narrow pulse with an unusually high pulsed fraction of ~70%. No pulsations are detected in the 2.0-10.0 keV range, where we derive an upper limit at the 99% level for the pulsed fraction of 28%. The pulsed emission is well described by a thermal blackbody model with a high temperature of 2.4x10^6 K. While no unambiguous signature of magnetar-like emission has been found in high-magnetic-eld radio pulsars, the X-ray characteristics of PSR J1119-6127 require alternate models from those of conventional thermal emission from neutron stars. In addition, PSR J1119-6127 is now the radio pulsar with the smallest characteristic age from which thermal X-ray emission has been detected

A 350-MHz GBT Survey of 50 Faint Fermi Gamma-ray Sources for Radio Millisecond Pulsars

We have used the Green Bank Telescope at 350MHz to search 50 faint, unidentified Fermi Gamma-ray sources for radio pulsations. So far, these searches have resulted in the discovery of 10 millisecond pulsars, which are plausible counterparts to these unidentified Fermi sources. Here we briefly describe this survey and the characteristics of the newly discovered MSPs.Comment: 4 pages, 2 figures, to appear in AIP Conference Proceedings of Pulsar Conference 2010 "Radio Pulsars: a key to unlock the secrets of the Universe", Sardinia, October 201

Chandra Smells a RRAT: X-ray Detection of a Rotating Radio Transient

"Rotating RAdio Transients" (RRATs) are a newly discovered astronomical phenomenon, characterised by occasional brief radio bursts, with average intervals between bursts ranging from minutes to hours. The burst spacings allow identification of periodicities, which fall in the range 0.4 to 7 seconds. The RRATs thus seem to be rotating neutron stars, albeit with properties very different from the rest of the population. We here present the serendipitous detection with the Chandra X-ray Observatory of a bright point-like X-ray source coincident with one of the RRATs. We discuss the temporal and spectral properties of this X-ray emission, consider counterparts in other wavebands, and interpret these results in the context of possible explanations for the RRAT population.Comment: 5 pages, 2 b/w figures, 1 color figure. To appear in the proceedings of "Isolated Neutron Stars", Astrophysics & Space Science, in pres

Pulsar Wind Nebulae with Bow Shocks: Non-thermal Radiation and Cosmic Ray Leptons

Pulsars with high spin-down power produce relativistic winds radiating a non-negligible fraction of this power over the whole electromagnetic range from radio to gamma-rays in the pulsar wind nebulae (PWNe). The rest of the power is dissipated in the interactions of the PWNe with the ambient interstellar medium (ISM). Some of the PWNe are moving relative to the ambient ISM with supersonic speeds producing bow shocks. In this case, the ultrarelativistic particles accelerated at the termination surface of the pulsar wind may undergo reacceleration in the converging flow system formed by the plasma outflowing from the wind termination shock and the plasma inflowing from the bow shock. The presence of magnetic perturbations in the flow, produced by instabilities induced by the accelerated particles themselves, is essential for the process to work. A generic outcome of this type of reacceleration is the creation of particle distributions with very hard spectra, such as are indeed required to explain the observed spectra of synchrotron radiation with photon indices Γ≲ 1.5. The presence of this hard spectral component is specific to PWNe with bow shocks (BSPWNe). The accelerated particles, mainly electrons and positrons, may end up containing a substantial fraction of the shock ram pressure. In addition, for typical ISM and pulsar parameters, the e+ released by these systems in the Galaxy are numerous enough to contribute a substantial fraction of the positrons detected as cosmic ray (CR) particles above few tens of GeV and up to several hundred GeV. The escape of ultrarelativistic particles from a BSPWN—and hence, its appearance in the far-UV and X-ray bands—is determined by the relative directions of the interstellar magnetic field, the velocity of the astrosphere and the pulsar rotation axis. In this respect we review the observed appearance and multiwavelength spectra of three different types of BSPWNe: PSR J0437-4715, the Guitar and Lighthouse nebulae, and Vela-like objects. We argue that high resolution imaging of such objects provides unique information both on pulsar winds and on the ISM. We discuss the interpretation of imaging observations in the context of the model outlined above and estimate the BSPWN contribution to the positron flux observed at the Earth

Working Conditions Of Chagas' Disease Patients In A Large Brazilian City.

This study evaluated the working conditions of Chagas' disease patients in the city of Campinas, São Paulo, focusing on two-hundred-fifty patients with steady employment and treated at the University Hospital (HC-FCM/Unicamp): 98% were working-age and 77.6% were men. The origin of the patients reflected the migratory process occurring among this population. Most of the patients had limited professional skills, while 63.6% had not finished primary school and 21.6% were illiterate. However, 63.6% were regularly employed under duly processed work contracts. Their jobs were mainly in general services (21.6%) and heavy industry (21.2%). Some 55% of the patients reported a monthly income less than or equal to U$100.00, and 40.4% reported having been fired at least once during the last ten years, in 8.9% of the cases because of a diagnosis of Chagas' disease. Of the patients undergoing pre-hiring physical examinations (57.2%), 9.1% were refused, 92.3% of whom due to positive serology for T. cruzi. Finally, 78.4% reported not belonging to a labor union. The study demonstrated the precarious working conditions and discrimination experienced by workers with Chagas' disease.15238138

Nutritional risks and colorectal cancer in a portuguese population

Licencia creative commons: Open Access bajo la licencia Creative Commons 4.4 CC BY-NC-SABackground: Food and nutrition as major causes of colorectal cancer (CRC) are still debatable. Aim of the study: This cross-sectional study in a Portuguese population aimed to characterize and identify "high-risk" diets/life-styles and explore their associations with colorectal cancer. Methods: In 70 colorectal cancer patients and 70 sex, age-matched subjects without cancer history, we evaluated: diet history and detailed nutrient intake (DIET-PLAN5 2002, UK), alcohol (amount, type, years), smoking (number packages/year, years), physical activity, co-morbidities and body mass index. Age-adjusted Relative Risks were calculated, Proportional Hazards models adjusted the analysis for multiple risk factors. Results: Smoking was a risk factor (1.90). Increased colorectal cancer risk regarding the lowest vs the highest intake quartile emerged for: vitamin B12 (3.41), cholesterol (3.15), total fat (2.87), saturated fat (1.98), animal protein (1.95), energy (1.85), alcohol (1.70), iron (1.49), refined carbohydrates (1.39). Reduced colorectal cancer risk for the highest vs the lowest intake quartile was found for: n-3 fatty acids (0.10), insoluble fiber/folate (0.15), flavonoids/vitamin E (0.25), isoflavones/beta-carotene (0.30), selenium (0.36), copper (0.41), vitamin B6 (0.46). Conclusion: Our results corroborated well-established risk factors and identified emergent nutrients. Prolonged excessive intake of macronutrients and some micronutrients concurrent with marked deficits of fiber and protective compounds were dominant in colorectal cancer and more significant than alcohol and smoking. The interaction diet-colorectal cancer is consistent and the relevance of new nutrients is emerging.info:eu-repo/semantics/publishedVersio